Means to resist distortion of a rotary regenerator matrix



P. E. BEAM, JR

Feb. 7, 1967 MEANS TO RESIST DISTORTION OF A ROTARY REGENERATOR MATRIX Filed March 29, 1965 ATTORNZ United States Patent 3,302,694 MEANS TO RESIST DISTORTION OF A ROTARY REGENERATQR MATRIX Paul E. Beam, Jr., Indianapolis, 11:11., assignor to General Motors Corporation, Detroit, MiClL, a corporation of Delaware Filed Mar. 29, 1965, Ser. No. 443,379 Claims. (Cl. 16510) My invention relates to rotary regenerators, that is, de vices in which a porous annular body, called a matrix, rotates slowly so that each part of the matrix passes alternately through two spaces where it is exposed to gases at different temperatures, the matrix carrying heat from the hotter to the cooler gas. In such devices, a seal is provided where the matrix passes from one space to the other through a diaphragm or bulkhead. Sealing is one of the diificult problems in such regenerators, since there ordinarily is a very considerable pressure drop from one space to the other in installations such as gas turbines. Because of the changes of temperature of the gases as they flow through the matrix, the matrix has a temperature gradient. Because of the temperature gradient, there is differential expansion which may, and ordinarily does, cause a distortion of the matrix so that it becomes slightly dished, or barrel-shaped, or spool-shaped. Of course, this distortion is very slight, but slight clearances at the seals can cause very wasteful leakage.

In response to this problem, various efforts have been made to provide a seal which distorts along with the matrix. Another approach is to construct a matrix so that the thermal distortion is eliminated or minimized. This invention relates to a structure which counteracts distortions of the matrix by use of conical end rims fixed to stitfeners in the matrix and which distort in the opposite direction to the matrix. While the invention is applicable to both axial flow and radial fiow regenerators, its preferred embodiment is in a radial flow regenerator having two seals which surround a matrix at the two points where it passes through a diaphragm separating one gas space from the other.

The principal object of the invention is to decrease the leakage of the seals of rotary regenerators and, therefore, improve the efficiency of power plants incorporating such regenerators. The nature of this invention and its advantages will be clear from the succeeding detailed description of the preferred embodiment thereof with reference to the accompanying drawings, wherein:

FIGURE 1 is a rather schematic cutaway view of a rotary regenerator embodying the invention, the view being taken on a plane perpendicular to the axis of rotation;

FIGURE 2 is an enlarged partial view of the matrix taken in the same plane as FIGURE 1, with parts cut away;

FIGURE 3 is a cross-section of the matrix taken on the plane indicated by the line 33 of FIGURE 2; and

FIGURE 4 is a schematic view of the matrix and the end rims separated from each other for the purpose of showing the effects of the thermal distortion on these members.

FIGURE 1 may be regarded as a simplified representation of the application of this invention to the regenerator of a gas turbine engine. In such an engine, a regenerator matrix is suitably supported in a housing 12 for rotation about an axis A so that it passes twice through a bulkhead or diaphragm 14. Main seals 16 and 18 surround the matrix where it passes through the diaphragm. The means to support the matrix for rotation about the axis and to locate the seals 16 and 18 are immaterial to this invention and Will not be described. Approximately one 3,302,694 Patented Feb. 7, 1967 third of the matrix is to the left of the diaphragm, moving through a space which is divided by the matrix into a cool air zone 20 which may be supplied by the compressor (not illustrated) of the gas turbine engine and a hot air zone 22 into which the air flows through the matrix. Combustion chambers (not illustrated) connected to the hot air zone 22 discharge through a turbine (not illustrated) into a hot gas zone 24 within the matrix at the other side of the diaphragm, from which the exhaust gas flows through the matrix to the space 26 from which it is discharged into the atmosphere.

Referring now also to FIGURES 2 and 3 for the preferred structure, the matrix 10 is of an annular drum shape having two conical end rims 28, each of which may include a ring or track 30 by which the matrix is supported and guided, and a ring gear 32 by which it is driven. Stiifeners 34 of relatively heavy section are spaced regularly around the periphery of the drum, extending from one rim to the other to couple the rims together rigidly and provide a squirrel cage type structure. The stitfeners have lugs 36 extending from their ends received in circumferential grooves in the inner faces of the end rims and held there by pins 38, which are inserted before the ring 30 is shrunk into place.

The spaces between the stiffeners 34 and extending from one rim to the other are filled with porous heat transfer material which consists of two types of elements. The first of these are rigidly spaced seal elements 40. Between each two seal elements there is a stack or pack of heat transfer elements 42 which may be called a core. It will be noted that the seal elements 40 have opposite marginal portions which extend radially from the elements 42. The elements 42 may be regarded as the core of the matrix and the elements 40 and 42 together constitute heat transfer material. These elements may be thin corrugated plates with the corrugations extending generally radially of the matrix so that small passages for air fiow are defined between adjacent plates and heat is readily exchanged between the air or gas and the thin plates of the heat transfer material. If desired, alternate plates of the heat transfer material may be flat and corrugated, or any other suitable form of heat exchange material may be employed. Further details of the type of matrix structure used are not deemed to be necessary to the disclosure of the invention.

As seen specifically in FIGURES 3 and 4, the end rims 28 are conical so that the widest portion of the matrix is at the cold side of the matrix and the narrowest portion is at the hot side of the matrix. Looking at FIGURE 4, the effects of the thermal gradient existing from the hot side to the cold side on the matrix 10 are schematically shown by the dashed lines. This distortion tends to bow or contort the matrix as shown by the arrows 44 and 46 in FIG- URE 4. It is this distortion caused by the thermal gradient which results in very ineffective sealing at the points where the matrix 10 passes through the bulkhead 14. To counteract this distortion, the subject invention employs conical end rims 28 which distort as shown by the dashed lines in FIGURE 4. The temperature gradient produces a moment on the conical end rims tending to rotate them about their centers of mass as shown by the arrows 48. Thus, the distortion of the end rims 28 is opposite to the distortion of the matrix 10. Now since these end rims are rigidly fastened to the stilfeners in matrix 10, the two opposing distortions counteract each other, thereby resulting in a minimum overall distortion of the matrix and effective sealing at the bulkhead.

Although there is no simple expression for the relationship for the parameters involved to result in a balancing of distortion, it is conceivable that such values for end rim angle, thickness, material, etc. can be found by experimentation. Hence, the desired result of no distortion in the regenerator matrix is obtainable by means of conventional research techniques.

Hence it can be seen that by the use of conical end rims rigidly secured to the matrix stifieners, the normal distortion caused by a thermal gradient across the matrix can be effectively counteracted, thereby reducing the overall distortion of the rotating matrix to a minimum and increasing the sealing effectiveness.

Although but one embodiment of the subject invention has been shown and described in detail, it should be clear to those skilled in the art to which it pertains, that it has many other uses and that many changes may be made thereto without departing from the scope of the invention.

I claim:

1. A rotary regenerator matrix comprising, in combination,

two mutually spaced coaxial annular rigid rims a body disposed between the rims and extending from one rim to the other, the rims being at the edges of the body the body having faces terminating at the edges of the rims and including heat exchange structure porous t0 fluid flow from face to face of the body between the rims the body including rigid members extending from one rim to the other and rigidly connected to the rims the matrix normally having a relatively cold side and a relatively hot side in operation characterized by the facts that the cross-section of the matrix is generally trapezoidal, narrower at the hot side than the cold side, with the body narrower at the hot side and the rims converging toward each other toward the hot side, so that stresses arising from differential thermal expansion due to temperature gradients in the rims and in the said rigid members are in opposition, thus tending to minimize thermal distortion of the matrix.

2. A matrix as recited in claim 1 in which the faces are inner and outer faces and the flow is radial.

3. A matrix as recited in claim 2 in which the said rigid members are circumferentially spaced stiifeners defining a squirrel cage structure with the rims.

4. A matrix as recited in claim 2 in which the rims are frusto-conical and the heat exchange body has a trapezoidal cross-section.

5. A matrix as recited in claim 2 in which the hot side is the inner side.

References Cited by the Examiner UNITED STATES PATENTS 3,186,479 6/1965 Mondt 16510 3,194,301 7/1965 Kovats 165-10 X FOREIGN PATENTS 1,121,635 1/1962 Germany.

MEYER PERLIN, Primary Examiner.

ROBERT A. OLEARY, Examiner.

A. W. DAVIS, Assistant Examiner. 

1. A ROTARY REGENERATOR MATRIX COMPRISING, IN COMBINATION, TWO MUTUALLY SPACED COAXIAL ANNULAR RIGID RIMS A BODY DISPOSED BETWEEN THE RIMS AND EXTENDING FROM ONE RIM TO THE OTHER, THE RIMS BEING AT THE EDGES OF THE BODY THE BODY HAVING FACES TERMINATING AT THE EDGES OF THE RIMS AND INCLUDING HEAT EXCHANGE STRUCTURE POROUS TO FLUID FLOW FROM FACE TO FACE OF THE BODY BETWEEN THE RIMS THE BODY INCLUDING RIGID MEMBERS EXTENDING FROM ONE RIM TO THE OTHER AND RIGIDLY CONNECTED TO THE RIMS THE MATRIX NORMALLY HAVING A RELATIVELY COLD SIDE AND A RELATIVELY HOT SIDE IN OPERATION CHARACTERIZED BY THE FACTS THAT THE CROSS-SECTION OF THE MATRIX IS GENERALLY TRAPEZOIDAL, NARROWER AT THE HOT SIDE THAN THE COLD SIDE, WITH THE BODY NARROWER AT THE HOT SIDE AND THE RIMS CONVERGING TOWARD EACH OTHER TOWARD THE HOT SIDE, SO THAT STRESSES ARISING FROM DIFFERENTIAL THERMAL EXPANSION DUE TO TEMPERATURE GRADIENTS IN THE RIMS AND IN THE SAID RIGID MEMBERS ARE IN OPPOSITION, THUS TENDING TO MINIMIZE THERMAL DISTORTION OF THE MATRIX. 